Liquid-contact device



June 6, 1950 w. w. KRAFT LIQUID coN'rAc'r DEVICE t v/Illlllfllllllllldtl I I f f 1 a 1 Filed Feb. 25, 1948 Paientedlune 6,1950' I LIQUID-CONTACT DEVICE Wheaton W. Kraft, Scandale, N. Y.,assignor to The Lummus Company, New York. N. Y., a

corporation of Delaware Application February z5, 194s, serial No. 10,604

3 claims. (ci. zei-114) In the recently issued patent to Koch 2,401,569

of June 4, 1946, a tray of the so-called Caskade" type'has beendisclosed. In such construction, the vapor and liquid are broughttogether in a series of staggered step-like zones or Caskades and thevapors or gases and liquid then pass up lan extended perforated surfacethrough which the liquid passes. The liquid then passes downwardly tothe next step of the Caskade while the vapors pass upward and out of thecolumn. Such a construction is claimed to be a substantial improvementover the standard type of bubble cap contact device in that it is moreflexible and more eillcient.

My invention relates to an improvement in a "Caskade" type of contactapparatus and more particularly to improvements in the arrangement ofthe Caskade stages for a further improvement in operating conditions.

More specifically, I provide for a material reduction of entrainment ofliquid in the released vapors by providing a particularly angularity forthe respective baille plates so that a greater travel of vapors or gasesis provided and by providing tion througha portion of an improvedCaskade type of vapor-liquid contact column.

The principal characteristic of a Caskade' type oi' contact columngenerally indicated at I0 in the attached drawing is the provision ofone or more liquid-vapor contact stages generally indicated at A. Theseconsist of a series of staggered overlapping `trough shaped decks ortroughs II, IIa, IIb, IIc, and I Id each of which is arranged to carryliquid from a downcomer trap or liquid reservoir I2 at one side of thecolumn to the next lower trap I2a on the other side of the column.Normally, a Weir I3 serves to maintain a predetermined height of liquidin the respective traps.

Each deck IIa, IIb, IIc, and IId has at its downstream side an upwardlyextending baille plate member generally indicated at I4, Ila, IIb, andIlc. These plate members are generally perforated at I5 for a purpose tobe hereinafter described, the lowermost perforation being at a levelsuch that a desired body of liquid will be carried on the deck.

In addition, all of the decks II have a downwardly projecting sealportion generally indicated at I6 which extends (in the case of alldecks except Ild) into the liquid maintained on the deck below to form aliquid type seal i'or the vapors tending to rise in the column.

In accordance with my invention, each of the baille plates I4 to I4cinclusive are inclined as at I8, Ita, I8b and I 8c in a particularmanner as hereinafter described.

In a liquid contact appartus of this type, liquid enteringtrap I2 fromdowncomer 20 as from an upper stage such as A: is fed into one oi theparallel vapor streams 22 entering from stage B below and the resultingliquid-vapor mixture is hurled violently against the solid lower portionof baille plate member I4, Ila, etc., with the velocity of the mixturecreating considerable centrifugal force as the mixture flows along andup the baille forcing all of the liquid and a portion of the vaporthrough the perforations I 5. As the load increases the froth is thrownhigher alongv the face of the bailles.

The liquid separates from the vapor on the opposite face of the baillein a vigorous bubbling action and ilows down .the baille to feed intothe next lower trough where the operation is repeated. As the liquidpasses through the last perforated baffle it drops into downcomer 20a tobe fed into the trap I2a below which in turn supplies liquid for stageC. Due to the stair-step arrangement of troughs there is no chance forliquid buildup, so that very large quantities of liquid can be handled.Moreover, since all the liquid passes into each trough successively, allthe liquid receives the same treatment. l

Due-to the violence of vapor-liquid mixing the liquid is broken up intovery line droplets so that high fractionating efilciency is obtainedeven with cold and relatively viscous oils such as found in absorbers.Furthermore, a large contacting surface is provided by the perforatedbaiiies.

Fundamentally the Caskade tray action is that of vapor-liquid mixing andthen separation bv mechanical means, namely centrifugal force, whichprovides many times the vapor-liquid separating fonce available in abubble tray de-A pending for separation only on the simple difference indensity between vapor and liquid.

In accordance with my invention, the tips I8. Ia, I8b, and I8c of thebailles Il, Ita, Ilb, and Hcvof one stage are directed to the high pointof the stage above and away from the entry side of the vapors so thatthe vapors are forced to take the longest vapor path before passingthrough the next above stage of decks. As will appear, the vapors asshown by the lines 22 11017 only must pass upwardly and transversely oithe column but must also reverse themselves through at least a 90 turnand in some cases through a greater angle in order to pass laterallyunder the decks Il and through the next above liquid reservoir in goingfrom stage B to stage A, for example. At the same time, the vapors passover the tips I8, etc. in a smooth streamlined fashion with a minimum ofresistance.

In accordance with my improvement it is possible to substantially reducethe entrainment which would otherwise be carried by vapors which haveundergone such a violent movement against the bailles. In view of thefact that the limitations of a column of this type are very oftendependent upon the eilciency of entrainment separation, it is thuspossible to materially increase the over all efficiency of the columnand efciency increases of as much as 25% may he expected.

While I have shown and described a. preferred form of embodiment of myinvention, I am aware that modifications may be made thereto and Itherefore desire a broad interpretation of my invention within the scopeand spirit of the description herein and the claims appendedhereinafter.

I claim:

1. A vapor-liquid contact devicecomprising a vertical column, aplurality of vertically-spaced, laterally inclined vapor-liquid contactstages in said column arranged forcascade liquid flow alternately fromopposite sides of the column, each stage being formed by a. series ofvertically and horizontally offset and overlapping liquid receivingdecks, the downstream side of each deck having a depending seal portionadapted to extend below the surface of the liquid on the deck beneath itto force vapors passing upwardly through the column to flow between thedecks and through the liquid on the decks, a perforated baffle platemember extending upwardly from the seal portion of eack deck and havinga curved upper tip inclined in a direction away from the upstream sideof the deck with Which it is associated, the lowermost perforation ofeach baiiie plate member being in a position to maintain a, body ofliquid on each deck.

2. A vapor-liquid contact device comprising a vertical column, aplurality of vertically spaced, laterally inclined vapor-liquid contactstages in said column arranged for cascade liquid iiow altendingupwardly from the seal portion of each deck and having a curved uppertip inclined in a direction away from the upstream side of the deck andtoward the higher point of the stage immediately thereabove, thelowermost perforation of each baille plate member being in a position tomaintain a body of liquid on each deck.

3. A vapor-liquid contact device comprising a vertical column, aplurality of reservoirs for liquid at different levels along oppositesides of said column, each of said reservoirs being adapted to receive,store, and discharge liquid, a plurality of pairs of vertically spaced,laterally inclined vapor-liquid contact stages in said column, each ofsaid stages extending from a higher reservoir to a lower reservoir onthe opposite side of the column, the stage below extending from saidlower reservoir to the next lower reservoir on the same side of thetower as said` higher reservoireach 4of said stages being formed by aseries of vertically and horizontally offset `and overlapping liquidreceiving decks, the downstream side of each deck having a dependingseal portion adapted to extend below the surface of the liquid on thedeck beneath it to ,force vapors passing upwardly through the column toflow between the decks and through the liquid on the decks, a perforatedbaille plate member extending upwardly from the seal portion of eachdeck and having a curved upper tip inclined in a direction away 4fromthe upstream side of the deck with which it is associated and toward thereservoir of the next higher stage, the lowermost perforation of eachbaiile plate member being in a position to maintain a body of liquid oneach deck.

WHEA'I'ON W. KRAFT.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,741,519 Huff Dec. 31, 19292,401,569 Koch June 4, 1946

